-
Notifications
You must be signed in to change notification settings - Fork 0
/
Code
324 lines (274 loc) · 7.43 KB
/
Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
Opening Input/Output Files:
// Opening input file in read-only mode
int fd1 = open(“sample.txt”, O_RDONLY);
if (fd1 == -1) {
perror("Open Failed For Input File:\n");
exit(1);
}
// Creating output file in write mode
int fd2 = open(“sample - compressed.txt”,
O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
if (fd2 == -1) {
perror("Open Failed For Output File:\n");
exit(1);
}
Function to Initialize and Create Min Heap:
#include <iostream>
#include <utility>
#include <vector>
using namespace std;
// Structure for tree nodes
struct Node {
char character;
int freq;
Node *l, *r;
Node(char c, int f)
: character(c)
, freq(f)
, l(nullptr)
, r(nullptr)
{
}
};
// Structure for min heap
struct Min_Heap {
int size;
vector<Node*> array;
Min_Heap(int s)
: size(s)
, array(s)
{
}
};
// Function to create min heap
Min_Heap* createAndBuildMin_Heap(char arr[], int freq[],
int unique_size)
{
int i;
// Initializing heap
Min_Heap* Min_Heap = new Min_Heap(unique_size);
// Initializing the array of pointers in minheap.
// Pointers pointing to new nodes of character
// and their frequency
for (i = 0; i < unique_size; ++i) {
Min_Heap->array[i] = new Node(arr[i], freq[i]);
}
int n = Min_Heap->size - 1;
for (i = (n - 1) / 2; i >= 0; --i) {
// Standard function for Heap creation
Heapify(Min_Heap, i);
}
return Min_Heap;
}
Function to Build and Create a Huffman Tree:
// Function to build Huffman Tree
struct Node* buildHuffmanTree(char arr[], int freq[],
int unique_size)
{
struct Node *l, *r, *top;
while (!isSizeOne(Min_Heap)) {
l = extractMinFromMin_Heap(Min_Heap);
r = extractMinFromMin_Heap(Min_Heap);
top = newNode('$', l->freq + r->freq);
top->l = l;
top->r = r;
insertIntoMin_Heap(Min_Heap, top);
}
return extractMinFromMin_Heap(Min_Heap);
}
Recursive Function to Print Binary Codes into Compressed File:
// Structure to store codes in compressed file
typedef struct code {
char k;
int l;
int code_arr[16];
struct code* p;
} code;
// Function to print codes into file
void printCodesIntoFile(int fd2, struct Node* root,
int t[], int top = 0)
{
int i;
if (root->l) {
t[top] = 0;
printCodesIntoFile(fd2, root->l, t, top + 1);
}
if (root->r) {
t[top] = 1;
printCodesIntoFile(fd2, root->r, t, top + 1);
}
if (isLeaf(root)) {
data = (code*)malloc(sizeof(code));
tree = (Tree*)malloc(sizeof(Tree));
data->p = NULL;
data->k = root->character;
tree->g = root->character;
write(fd2, &tree->g, sizeof(char));
for (i = 0; i < top; i++) {
data->code_arr[i] = t[i];
}
tree->len = top;
write(fd2, &tree->len, sizeof(int));
tree->dec
= convertBinaryToDecimal(data->code_arr, top);
write(fd2, &tree->dec, sizeof(int));
data->l = top;
data->p = NULL;
if (k == 0) {
front = rear = data;
k++;
}
else {
rear->p = data;
rear = rear->p;
}
}
}
Function to Compress the File by Substituting Characters with their Huffman Codes:
// Function to compress file
void compressFile(int fd1, int fd2, unsigned char a)
{
char n;
int h = 0, i;
// Codes are written into file in bit by bit format
while (read(fd1, &n, sizeof(char)) != 0) {
rear = front;
while (rear->k != n && rear->p != NULL) {
rear = rear->p;
}
if (rear->k == n) {
for (i = 0; i < rear->l; i++) {
if (h < 7) {
if (rear->code_arr[i] == 1) {
a++;
a = a << 1;
h++;
}
else if (rear->code_arr[i] == 0) {
a = a << 1;
h++;
}
}
else if (h == 7) {
if (rear->code_arr[i] == 1) {
a++;
h = 0;
}
else {
h = 0;
}
write(fd2, &a, sizeof(char));
a = 0;
}
}
}
}
for (i = 0; i < 7 - h; i++) {
a = a << 1;
}
write(fd2, &a, sizeof(char));
}
Function to Build Huffman Tree from Data Extracted from Compressed File:
typedef struct Tree {
char g;
int len;
int dec;
struct Tree* f;
struct Tree* r;
} Tree;
// Function to extract Huffman codes
// from a compressed file
void ExtractCodesFromFile(int fd1)
{
read(fd1, &t->g, sizeof(char));
read(fd1, &t->len, sizeof(int));
read(fd1, &t->dec, sizeof(int));
}
// Function to rebuild the Huffman tree
void ReBuildHuffmanTree(int fd1, int size)
{
int i = 0, j, k;
tree = (Tree*)malloc(sizeof(Tree));
tree_temp = tree;
tree->f = NULL;
tree->r = NULL;
t = (Tree*)malloc(sizeof(Tree));
t->f = NULL;
t->r = NULL;
for (k = 0; k < size; k++) {
tree_temp = tree;
ExtractCodesFromFile(fd1);
int bin[MAX], bin_con[MAX];
for (i = 0; i < MAX; i++) {
bin[i] = bin_con[i] = 0;
}
convertDecimalToBinary(bin, t->dec, t->len);
for (i = 0; i < t->len; i++) {
bin_con[i] = bin[i];
}
for (j = 0; j < t->len; j++) {
if (bin_con[j] == 0) {
if (tree_temp->f == NULL) {
tree_temp->f
= (Tree*)malloc(sizeof(Tree));
}
tree_temp = tree_temp->f;
}
else if (bin_con[j] == 1) {
if (tree_temp->r == NULL) {
tree_temp->r
= (Tree*)malloc(sizeof(Tree));
}
tree_temp = tree_temp->r;
}
}
tree_temp->g = t->g;
tree_temp->len = t->len;
tree_temp->dec = t->dec;
tree_temp->f = NULL;
tree_temp->r = NULL;
tree_temp = tree;
}
}
Function to Decompress the Compressed File:
void decompressFile(int fd1, int fd2, int f)
{
int inp[8], i, k = 0;
unsigned char p;
read(fd1, &p, sizeof(char));
convertDecimalToBinary(inp, p, 8);
tree_temp = tree;
for (i = 0; i < 8 && k < f; i++) {
if (!isroot(tree_temp)) {
if (i != 7) {
if (inp[i] == 0) {
tree_temp = tree_temp->f;
}
if (inp[i] == 1) {
tree_temp = tree_temp->r;
}
}
else {
if (inp[i] == 0) {
tree_temp = tree_temp->f;
}
if (inp[i] == 1) {
tree_temp = tree_temp->r;
}
if (read(fd1, &p, sizeof(char)) != 0) {
convertDecimalToBinary(inp, p, 8);
i = -1;
}
else {
break;
}
}
}
else {
k++;
write(fd2, &tree_temp->g, sizeof(char));
tree_temp = tree;
i--;
}
}
}